Category: Safety

Why do speeding crashes in Chicago lead to worse injuries?

November 21, 2013 / / 6 Comments

Don’t git behind me. Photo by Richard Masoner. 

A discussion about Chicagoans’ proclivity for tailgating (on a post about speed cameras) prompted me to look at the prevalence of this in causing crashes. I looked at the three-year period of 2010-2012 first, mainly so the numbers wouldn’t be so large, and left this information in a comment. But considering the prerequisites* for a crash to be reported in this dataset, and my desire to compare two multi-year periods, I switched my analysis to the single four-year period 2009-2012.

2009-2012

Total crashes: 318,193. Total fatalities: 554 people.

Tailgating crashes

62,080 crashes, 19.53% of all crash types

Tailgating crashes, injuries breakdown:

  • Killed: .0012 (this represents the number of deaths per crash). 75 people died in these crashes, representing 13.54% of all deaths.
  • Incapacitating injuries: 8.53% (the average distribution of people’s injuries in all tailgating crashes)
  • Non-Incapacitating: 46.32%
  • Possible injury: 45.15%

The share of all crash types that are tailgating has increased steadily from 18.11% in 2009 to 20.79% in 2012.

Speeding crashes

10,339 crashes, 3.24% of all crash types

Speeding injuries:

  • Killed: .0118 (this represents the number of deaths per crash). 122 people died in these crashes, representing 22.02% of all deaths.
  • Incapacitating injuries: 15.55% (the average distribution of people’s injuries in all speeding crashes)
  • Non-Incapacitating: 51.95%
  • Possible injury: 32.50%

The share of all crash types that are tailgating has decreased slightly from 3.72% in 2009 to 3.02% in 2012. While speeding leads to fewer crashes, it leads to a greater incidence of death and serious injury. The probability of a speeding crash leading to at least one death seems to stay steady through the period while the probability of seeing a person with an incapacitating injury versus a different kind of injury varies more, but not so much in a range that overlaps the rates for tailgating crashes.

A future comparison at injuries should look at the top crash causes for death and serious injury.

N/A and Unable to determine crashes

237,729 crashes, 74.71% of all crash types

N/A and unable to determine injuries:

  • Killed: .0013 (this represents the number of deaths per crash). 305 people died in these crashes, representing 55.05% of all deaths.
  • Incapacitating injuries: 9.38% (the average distribution of people’s injuries in all N/A crashes)
  • Non-Incapacitating: 48.26%
  • Possible injury: 42.35%

Notes

Updated December 4, 2013

I updated the wording on how to interpret these numbers. For example, previously for “killed” there was a percentage saying this number represented the amount of crashes that had at least one death. This wasn’t accurate: the same number represents a rate of deaths per crash of that type. Injury percentages represent the distribution of injury types experienced by all the people injured in crashes of that type.

Reliability

Analyzing crash causes is not very reliable as 45.60% of the reported crashes in 2012 had “N/A” or “unable to determine” listed as the primary cause! The third and fourth most frequently ascribed causes were the two tailgating codes (described below). There are some crashes that had the one of these two causes in the secondary cause field but I haven’t calculated that.

Cause code descriptions

Each crash has two cause codes. For tailgating crashes I searched for reports where “failing to reduce speed to avoid crash” or “following too closely” in either the primary or secondary cause field (it’s possible that a report had both of these causes ascribed). For speeding crashes I searched for “speed excessive for conditions” or “exceeding speed limit” in either the primary or secondary cause fields.

Prerequisites

This data excludes crashes where there was no injury or no property damage greater than $500 (2005 to 2008) and $1,500 (2009 to 2012). You cannot compare the two datasets when you want to see a share of all crashes because the number of “all crashes” will be underreported in the second dataset.

Queries

These are some of the MySQL queries I used to get the data out of my own crash database (I’m figuring out ways to make it public, using a shared login). “Cause 1 code” indicates the primary cause of the crash according to the police officer’s judgement. “Cause 2 code” indicates the secondary cause of the crash according to the police officer’s judgement.

1. Crash cause reliability: SELECt count(casenumber), sum(`Total killed`), `Cause2`, `Cause 2 code` FROM `CrashExtract_Chicago` WHERE year = 12 GROUP BY `Cause 2 code`  ORDER BY cast(`Cause 2 code` as signed)

2. Speeding crashes: SELECT count(casenumber), sum(`Total killed`), sum(`totalInjuries`), sum(`A injuries`), sum(`B injuries`), sum(`C injuries`) FROM `CrashExtract_Chicago` WHERE (`Cause 1 code` = 1 OR `Cause 1 code` = 27 OR `Cause 2 code` = 1 or `Cause 2 code` = 27) AND year > 8

3. Tailgating crashes: SELECT count(casenumber), sum(`Total killed`), sum(`totalInjuries`), sum(`A injuries`), sum(`B injuries`), sum(`C injuries`) FROM `CrashExtract_Chicago` WHERE (`Cause 1 code` = 3 OR `Cause 1 code` = 28 OR `Cause 2 code` = 3 or `Cause 2 code` = 28) AND year > 8

4. N/A and Unable to determine crashes: SELECT count(casenumber), sum(`Total killed`), sum(`totalInjuries`), sum(`A injuries`), sum(`B injuries`), sum(`C injuries`) FROM `CrashExtract_Chicago` WHERE (`Cause 1 code` = 18 OR `Cause 1 code` = 99) AND year > 8

When did everyone start caring about bicyclists dying?

November 13, 2013 / / 18 Comments

A Plague of Cyclists appear to run cars off the road on The Weekly Standard’s cover.

A couple weeks ago a bunch of journalists from major international news outlets were having drinks somewhere (maybe The Billy Goat Tavern in Chicago’s basement) and wrote the same story.

Actually, they didn’t, but it’s surprisingly weird how close they were.

On Sunday the New York Times published “Is It O.K. To Kill Cyclists?”. Next, on Monday, Crain’s Chicago Business published “Why everyone hates bicyclists—and why they hate everyone back”.

Daniel Duane’s op-ed in NYT garnered a lot of response (7 of them are linked here, which doesn’t include Crain’s or The Weekly Standard). The Economist responded to the NYT article with “Cycling v cars: The American right-of-way” saying we should adopt laws like the Netherlands and gave several examples there of who’s liable for a crash between a car and bike (nearly always the driver). Bike Snob wrote the response I most agree with. Karen Altes of Tiny Fix Bike Gang got pissed. Twin City Sidewalks (in Minneapolis/St. Paul) wrote that “bicyclists need to stop blaming themselves for dangerous roads”, referring to the bicyclist in question, Daniel Duane, the NYT op-ed contributor.

Tanya Snyder, writing for one of my employer’s sister blogs Streetsblog Capitol Hill, headlined her own roundup post, “The Times Blows a Chance to Tackle America’s Broken Traffic Justice System”. Andrew Smith at Seattle Transit Blog said that he gave up cycling to work in the first week he tried it. Brian McEntee wrote on his blog Tales from the Sharrows about two scenarios to consider about “following laws” (which isn’t what cyclists or drivers should be aiming for).

David Alpert, who runs a Streetsblog-like blog called Greater Greater Washington, said that it’s not okay to kill cyclists, “but if a spate of other op-eds are any indication, it’s sure okay to hate them and the facilities they ask for in a quest for safety”. BikeBlogNYC later published myriad examples of how streets continue killing everyone who’s not driving a car.

Then The Weekly Standard published something very similar to Duane’s piece. I don’t know when – it’s in the issue marked for November 18, but I believe it went up Monday, with a sweet cover. It went by two names. On the cover, “A Plague of Bicyclists” (by Christopher Caldwell) and on the site, “Drivers Get Rolled: Bicyclists are making unreasonable claims to the road—and winning”.

Most of the proceeding discussions revolve around “who’s right”. And the Economist skirts discussing the answer and instead just gives the answer: the bicyclist, because they’re the ones who die.

When you are driving in the Netherlands, you have to be more careful than you would when driving in America. Does this result in rampant injustice to drivers when accidents occur? No. It results in far fewer accidents. As the ANWB [Royal Dutch Touring Club, like the AAA] says, some drivers may think the liability treatment gives cyclists “a blank check to ignore the rules. But a cyclist is not going to deliberately ride through a red light thinking: ‘I won’t have to pay the damages anyway.’ He is more likely to be influenced by the risk that he will land in the hospital.”

I like what Evan Jenkins, a sometimes urbanist blogger studying mathematics at University of Chicago, wrote on his Twitter timeline:

That’s encouraging. He linked to several of his past articles about cyclist murder.

 

What’s also funny about this weekend’s bike-journo-fest is that Whet Moser, writing for Chicago Magazine, interviewed me two weeks ago about bike infrastructure and penned this uncomplicated, unruffled but comprehensive article saying “drivers and cyclists don’t have to be angry and fearful…with smart planning, a city can design safe roads for all.”

Chicago has started on that path. You know what might influence more change than any bike lane built? Speed cameras. And no, I won’t let them be removed.

Updated multiple times to add more responses to Duane’s op-ed. 

Desplaines Street bike lane design facilitates right hooks for bicyclists

September 16, 2013 / / 4 Comments

Photo 1 of 2: At Randolph Street I approach the “mixing zone” and position my bicycle to ride from the bike lane to the left side of the drivers waiting to turn right. 

In some of my social circles where bicycling is frequently discussed (with fellow transportation planners, advocates, or just people who bike commute frequently) we talk about Chicago’s new protected bike lanes, which started appearing in 2011.

The subject of their design is brought forth: they exacerbate turning conflicts between bicyclists going straight and drivers turning right (and to a lesser extent, left). Participants in these discussions usually express appreciation for the protected bike lanes, largely because of their ability to  reduce injuries overall and influence in bringing new people to bicycling, but are hard pressed to ignore this issue.

The issue is created in some instances when bicyclists are removed from sight of drivers because the bike lane is separated from the travel lanes by a vision-blocking lane of parked cars. However, the Chicago Department of Transportation has attempted to mitigate the turning issue by creating “mixing zones” where turning cars are and through-bicycles are mixed into the same, very wide lane prior to the intersection. When there is a green light, drivers typically merge into the mixing zone without much deceleration and then make the turn regardless of the bicyclist’s position.

Allowing turning cars and through-bicycles to go through these movements in the same place at the same time is a situation of incompatible demands.

Photo 2 of 2: I apparently didn’t position myself far enough to the left because the driver of this black Toyota turned right across my path. 

It’s highly unclear where the bicyclist is supposed to go and how they’re supposed to maneuver themselves in the mixing zone. If the bicyclist follows the lane and then the sharrows, they will be stuck behind cars. One of the pavement markings shows a small arrow above a bicycle symbol possible indicating that bicyclists must turn here (even though a sign says bicyclists and buses don’t have to turn from the lane).

The mixing zones on Desplaines Street are the worst at this, possibly because of the street’s nature as one that moves drivers exiting the city onto streets that lead into the Kennedy Expressway. People are gunning for the highway to get home and people bicycling tend to be in the way.

Additionally, the mixing zones on Desplaines Street differ from other protected bike lane installations (like the first one on Kinzie and subsequent ones on Elston, 18th, and Milwaukee) in that they lack the green lanes that CDOT has been using to highlight where car traffic crosses bike lane traffic.

Desplaines Street has another issue that arises when the signal is red and a bicyclist and a driver are both waiting for a green light. The bicyclist is between the car and the curb. The driver then makes a right turn on red (disregard whether or not a sign control makes this illegal) across the path of the stopped bicyclist. No harm done, right? Maybe, but there are a couple possibilities where this could be dangerous: the driver makes this movement as the light turns green and the bicyclist is attempting to move straight. Or there’s the possibility that the bicyclist also wants to turn right and the driver and bicyclist do so simultaneously without accommodating what the other may be doing. Both situations could lead to the dreaded “right hook”.

The driver of this white Hyundai makes a legal right turn from a “mixing zone” to Madison Street. However, what if the bicyclist wanted to also turn right, or the driver made this as the light was turning green?

The solution to the incompatible desire for one group of roadway users to turn and for the other group to go straight is to separate their movements with traffic signals, which CDOT has done on Dearborn Street.

With these situations in mind, it’s not unexpected to see a bicyclist move through the intersection on a red light to avoid a potential incident at the intersection, the site of most bike-car crashes. CDOT has reported that the red light compliance of people bicycling on Dearborn Street – the only street with bike-only signals – “has increased from only 31 percent of cyclists stopping for reds before the lanes and bike-specific traffic signals were installed, to 81 percent afterwards”.

I don’t think there’s not a problem with protected bike lanes but their precarious design in Chicago as well as the variations within Chicago and across the United States.

Department of Road Diets: the carbon tax

September 16, 2013 / / 6 Comments

Grand Avenue over the Kennedy Expressway. Its four lanes look like this – empty – most of the day. But then there are times of the day where people who bike, take the bus, and drive all need to “share the road”. That failed strategy has led to increased road rage, slow transit, and dead bicyclists. Time to put roads like this on a diet. 

My friend Brandon sent me an article about the one-page solution to (mitigating) climate change in the United States that NPR posted this summer.

But Henry Jacoby, an economist at MIT’s business school, says there’s really just one thing you need to do to solve the problem: Tax carbon emissions.

“If you let the economists write the legislation,” Jacoby says, “it could be quite simple.” He says he could fit the whole bill on one page.

Basically, Jacoby would tax fossil fuels in proportion to the amount of carbon they release. That would make coal, oil and natural gas more expensive. That’s it; that’s the whole plan.

This new carbon tax would support different infrastructure construction and expanded government agencies with which to manage it. It would support a Department of Road Diets. Road diets are projects that reduce the number of lanes for cars on a roadway, either by reducing the width of the roadway, or converting the general purpose lanes to new uses, like quickly moving buses or giving bicycles dedicated space.

See, in the carbon taxed future, people will want to drive less and use more efficient modes of transportation like transit and bicycles. And those uses will need their own space because the status quo in our cities (except the ones in the Netherlands) of having each mode compete for the same space isn’t working. It results in frustration, delay, and death.

Enter the Department of Road Diets. We have millions of miles of roadways that will need to go on diets so a department dedicated to such transformation would be useful. The agency would be in charge of finding too-wide roads and systematically putting them on diets, I mean, changing their cross section to less carbon-intensive uses.